mbedtls/tests/suites/test_suite_entropy.function

/* BEGIN_HEADER */
#include "mbedtls/entropy.h"
#include "mbedtls/entropy_poll.h"
#include "mbedtls/md.h"
#include "string.h"

typedef enum
{
    DUMMY_CONSTANT_LENGTH, /* Output context->length bytes */
    DUMMY_REQUESTED_LENGTH, /* Output whatever length was requested */
    DUMMY_FAIL, /* Return an error code */
} entropy_dummy_instruction;

typedef struct
{
    entropy_dummy_instruction instruction;
    size_t length; /* Length to return for DUMMY_CONSTANT_LENGTH */
    size_t calls; /* Incremented at each call */
} entropy_dummy_context;

/*
 * Dummy entropy source
 *
 * If data is NULL, write exactly the requested length.
 * Otherwise, write the length indicated by data or error if negative
 */
static int entropy_dummy_source( void *arg, unsigned char *output,
                                 size_t len, size_t *olen )
{
    entropy_dummy_context *context = arg;
    ++context->calls;

    switch( context->instruction )
    {
        case DUMMY_CONSTANT_LENGTH:
            *olen = context->length;
            break;
        case DUMMY_REQUESTED_LENGTH:
            *olen = len;
            break;
        case DUMMY_FAIL:
            return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
    }

    memset( output, 0x2a, *olen );
    return( 0 );
}

/*
 * Ability to clear entropy sources to allow testing with just predefined
 * entropy sources. This function or tests depending on it might break if there
 * are internal changes to how entropy sources are registered.
 *
 * To be called immediately after mbedtls_entropy_init().
 *
 * Just resetting the counter. New sources will overwrite existing ones.
 * This might break memory checks in the future if sources need 'free-ing' then
 * as well.
 */
static void entropy_clear_sources( mbedtls_entropy_context *ctx )
{
    ctx->source_count = 0;
}

#if defined(MBEDTLS_ENTROPY_NV_SEED)
/*
 * NV seed read/write functions that use a buffer instead of a file
 */
static unsigned char buffer_seed[MBEDTLS_ENTROPY_BLOCK_SIZE];

int buffer_nv_seed_read( unsigned char *buf, size_t buf_len )
{
    if( buf_len != MBEDTLS_ENTROPY_BLOCK_SIZE )
        return( -1 );

    memcpy( buf, buffer_seed, MBEDTLS_ENTROPY_BLOCK_SIZE );
    return( 0 );
}

int buffer_nv_seed_write( unsigned char *buf, size_t buf_len )
{
    if( buf_len != MBEDTLS_ENTROPY_BLOCK_SIZE )
        return( -1 );

    memcpy( buffer_seed, buf, MBEDTLS_ENTROPY_BLOCK_SIZE );
    return( 0 );
}

/*
 * NV seed read/write helpers that fill the base seedfile
 */
static int write_nv_seed( unsigned char *buf, size_t buf_len )
{
    FILE *f;

    if( buf_len != MBEDTLS_ENTROPY_BLOCK_SIZE )
        return( -1 );

    if( ( f = fopen( MBEDTLS_PLATFORM_STD_NV_SEED_FILE, "w" ) ) == NULL )
        return( -1 );

    if( fwrite( buf, 1, MBEDTLS_ENTROPY_BLOCK_SIZE, f ) !=
                    MBEDTLS_ENTROPY_BLOCK_SIZE )
        return( -1 );

    fclose( f );

    return( 0 );
}

int read_nv_seed( unsigned char *buf, size_t buf_len )
{
    FILE *f;

    if( buf_len != MBEDTLS_ENTROPY_BLOCK_SIZE )
        return( -1 );

    if( ( f = fopen( MBEDTLS_PLATFORM_STD_NV_SEED_FILE, "rb" ) ) == NULL )
        return( -1 );

    if( fread( buf, 1, MBEDTLS_ENTROPY_BLOCK_SIZE, f ) !=
                    MBEDTLS_ENTROPY_BLOCK_SIZE )
        return( -1 );

    fclose( f );

    return( 0 );
}
#endif /* MBEDTLS_ENTROPY_NV_SEED */
/* END_HEADER */

/* BEGIN_DEPENDENCIES
 * depends_on:MBEDTLS_ENTROPY_C
 * END_DEPENDENCIES
 */

/* BEGIN_CASE */
void entropy_init_free( int reinit )
{
    mbedtls_entropy_context ctx;

    /* Double free is not explicitly documented to work, but it is convenient
     * to call mbedtls_entropy_free() unconditionally on an error path without
     * checking whether it has already been called in the success path. */

    mbedtls_entropy_init( &ctx );
    mbedtls_entropy_free( &ctx );

    if( reinit )
        mbedtls_entropy_init( &ctx );
    mbedtls_entropy_free( &ctx );

    /* This test case always succeeds, functionally speaking. A plausible
     * bug might trigger an invalid pointer dereference or a memory leak. */
    goto exit;
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_ENTROPY_NV_SEED:MBEDTLS_FS_IO */
void entropy_seed_file( char * path, int ret )
{
    mbedtls_entropy_context ctx;

    mbedtls_entropy_init( &ctx );

    TEST_ASSERT( mbedtls_entropy_write_seed_file( &ctx, path ) == ret );
    TEST_ASSERT( mbedtls_entropy_update_seed_file( &ctx, path ) == ret );

exit:
    mbedtls_entropy_free( &ctx );
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_ENTROPY_NV_SEED:MBEDTLS_FS_IO */
void entropy_write_base_seed_file( int ret )
{
    mbedtls_entropy_context ctx;

    mbedtls_entropy_init( &ctx );

    TEST_ASSERT( mbedtls_entropy_write_seed_file( &ctx, MBEDTLS_PLATFORM_STD_NV_SEED_FILE ) == ret );
    TEST_ASSERT( mbedtls_entropy_update_seed_file( &ctx, MBEDTLS_PLATFORM_STD_NV_SEED_FILE ) == ret );

exit:
    mbedtls_entropy_free( &ctx );
}
/* END_CASE */

/* BEGIN_CASE */
void entropy_no_sources( )
{
    mbedtls_entropy_context ctx;
    unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];

    mbedtls_entropy_init( &ctx );
    entropy_clear_sources( &ctx );
    TEST_EQUAL( mbedtls_entropy_func( &ctx, buf, sizeof( buf ) ),
                MBEDTLS_ERR_ENTROPY_NO_SOURCES_DEFINED );

exit:
    mbedtls_entropy_free( &ctx );
}
/* END_CASE */

/* BEGIN_CASE */
void entropy_too_many_sources(  )
{
    mbedtls_entropy_context ctx;
    size_t i;
    entropy_dummy_context dummy = {DUMMY_REQUESTED_LENGTH, 0, 0};

    mbedtls_entropy_init( &ctx );

    /*
     * It's hard to tell precisely when the error will occur,
     * since we don't know how many sources were automatically added.
     */
    for( i = 0; i < MBEDTLS_ENTROPY_MAX_SOURCES; i++ )
        (void) mbedtls_entropy_add_source( &ctx, entropy_dummy_source, &dummy,
                                           16, MBEDTLS_ENTROPY_SOURCE_WEAK );

    TEST_ASSERT( mbedtls_entropy_add_source( &ctx, entropy_dummy_source, &dummy,
                                             16, MBEDTLS_ENTROPY_SOURCE_WEAK )
                 == MBEDTLS_ERR_ENTROPY_MAX_SOURCES );

exit:
    mbedtls_entropy_free( &ctx );
}
/* END_CASE */

/* BEGIN_CASE depends_on:ENTROPY_HAVE_STRONG */
void entropy_func_len( int len, int ret )
{
    mbedtls_entropy_context ctx;
    unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE + 10] = { 0 };
    unsigned char acc[MBEDTLS_ENTROPY_BLOCK_SIZE + 10] = { 0 };
    size_t i, j;

    mbedtls_entropy_init( &ctx );

    /*
     * See comments in mbedtls_entropy_self_test()
     */
    for( i = 0; i < 8; i++ )
    {
        TEST_ASSERT( mbedtls_entropy_func( &ctx, buf, len ) == ret );
        for( j = 0; j < sizeof( buf ); j++ )
            acc[j] |= buf[j];
    }

    if( ret == 0 )
        for( j = 0; j < (size_t) len; j++ )
            TEST_ASSERT( acc[j] != 0 );

    for( j = len; j < sizeof( buf ); j++ )
        TEST_ASSERT( acc[j] == 0 );

exit:
    mbedtls_entropy_free( &ctx );
}
/* END_CASE */

/* BEGIN_CASE */
void entropy_source_fail( char * path )
{
    mbedtls_entropy_context ctx;
    unsigned char buf[16];
    entropy_dummy_context dummy = {DUMMY_FAIL, 0, 0};

    mbedtls_entropy_init( &ctx );

    TEST_ASSERT( mbedtls_entropy_add_source( &ctx, entropy_dummy_source,
                                             &dummy, 16,
                                             MBEDTLS_ENTROPY_SOURCE_WEAK )
                 == 0 );

    TEST_ASSERT( mbedtls_entropy_func( &ctx, buf, sizeof( buf ) )
                 == MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
    TEST_ASSERT( mbedtls_entropy_gather( &ctx )
                 == MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
#if defined(MBEDTLS_FS_IO) && defined(MBEDTLS_ENTROPY_NV_SEED)
    TEST_ASSERT( mbedtls_entropy_write_seed_file( &ctx, path )
                 == MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
    TEST_ASSERT( mbedtls_entropy_update_seed_file( &ctx, path )
                 == MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
#else
    ((void) path);
#endif

exit:
    mbedtls_entropy_free( &ctx );
}
/* END_CASE */

/* BEGIN_CASE */
void entropy_threshold( int threshold, int chunk_size, int result )
{
    mbedtls_entropy_context ctx;
    entropy_dummy_context strong =
        {DUMMY_CONSTANT_LENGTH, MBEDTLS_ENTROPY_BLOCK_SIZE, 0};
    entropy_dummy_context weak = {DUMMY_CONSTANT_LENGTH, chunk_size, 0};
    unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE] = { 0 };
    int ret;

    mbedtls_entropy_init( &ctx );
    entropy_clear_sources( &ctx );

    /* Set strong source that reaches its threshold immediately and
     * a weak source whose threshold is a test parameter. */
    TEST_ASSERT( mbedtls_entropy_add_source( &ctx, entropy_dummy_source,
                                     &strong, 1,
                                     MBEDTLS_ENTROPY_SOURCE_STRONG ) == 0 );
    TEST_ASSERT( mbedtls_entropy_add_source( &ctx, entropy_dummy_source,
                                     &weak, threshold,
                                     MBEDTLS_ENTROPY_SOURCE_WEAK ) == 0 );

    ret = mbedtls_entropy_func( &ctx, buf, sizeof( buf ) );

    if( result >= 0 )
    {
        TEST_ASSERT( ret == 0 );
#if defined(MBEDTLS_ENTROPY_NV_SEED)
        /* If the NV seed functionality is enabled, there are two entropy
         * updates: before and after updating the NV seed. */
        result *= 2;
#endif
        TEST_ASSERT( weak.calls == (size_t) result );
    }
    else
    {
        TEST_ASSERT( ret == result );
    }

exit:
    mbedtls_entropy_free( &ctx );
}
/* END_CASE */

/* BEGIN_CASE */
void entropy_calls( int strength1, int strength2,
                    int threshold, int chunk_size,
                    int result )
{
    /*
     * if result >= 0: result = expected number of calls to source 1
     * if result < 0: result = expected return code from mbedtls_entropy_func()
     */

    mbedtls_entropy_context ctx;
    entropy_dummy_context dummy1 = {DUMMY_CONSTANT_LENGTH, chunk_size, 0};
    entropy_dummy_context dummy2 = {DUMMY_CONSTANT_LENGTH, chunk_size, 0};
    unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE] = { 0 };
    int ret;

    mbedtls_entropy_init( &ctx );
    entropy_clear_sources( &ctx );

    TEST_ASSERT( mbedtls_entropy_add_source( &ctx, entropy_dummy_source,
                                             &dummy1, threshold,
                                             strength1 ) == 0 );
    TEST_ASSERT( mbedtls_entropy_add_source( &ctx, entropy_dummy_source,
                                             &dummy2, threshold,
                                             strength2 ) == 0 );

    ret = mbedtls_entropy_func( &ctx, buf, sizeof( buf ) );

    if( result >= 0 )
    {
        TEST_ASSERT( ret == 0 );
#if defined(MBEDTLS_ENTROPY_NV_SEED)
        /* If the NV seed functionality is enabled, there are two entropy
         * updates: before and after updating the NV seed. */
        result *= 2;
#endif
        TEST_ASSERT( dummy1.calls == (size_t) result );
    }
    else
    {
        TEST_ASSERT( ret == result );
    }

exit:
    mbedtls_entropy_free( &ctx );
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_ENTROPY_NV_SEED:MBEDTLS_FS_IO */
void nv_seed_file_create(  )
{
    unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];

    memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE );

    TEST_ASSERT( write_nv_seed( buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) == 0 );
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_ENTROPY_NV_SEED:MBEDTLS_FS_IO:MBEDTLS_PLATFORM_NV_SEED_ALT */
void entropy_nv_seed_std_io(  )
{
    unsigned char io_seed[MBEDTLS_ENTROPY_BLOCK_SIZE];
    unsigned char check_seed[MBEDTLS_ENTROPY_BLOCK_SIZE];

    memset( io_seed, 1, MBEDTLS_ENTROPY_BLOCK_SIZE );
    memset( check_seed, 0, MBEDTLS_ENTROPY_BLOCK_SIZE );

    mbedtls_platform_set_nv_seed( mbedtls_platform_std_nv_seed_read,
                                  mbedtls_platform_std_nv_seed_write );

    /* Check if platform NV read and write manipulate the same data */
    TEST_ASSERT( write_nv_seed( io_seed, MBEDTLS_ENTROPY_BLOCK_SIZE ) == 0 );
    TEST_ASSERT( mbedtls_nv_seed_read( check_seed, MBEDTLS_ENTROPY_BLOCK_SIZE ) ==
                    MBEDTLS_ENTROPY_BLOCK_SIZE );

    TEST_ASSERT( memcmp( io_seed, check_seed, MBEDTLS_ENTROPY_BLOCK_SIZE ) == 0 );

    memset( check_seed, 0, MBEDTLS_ENTROPY_BLOCK_SIZE );

    /* Check if platform NV write and raw read manipulate the same data */
    TEST_ASSERT( mbedtls_nv_seed_write( io_seed, MBEDTLS_ENTROPY_BLOCK_SIZE ) ==
                    MBEDTLS_ENTROPY_BLOCK_SIZE );
    TEST_ASSERT( read_nv_seed( check_seed, MBEDTLS_ENTROPY_BLOCK_SIZE ) == 0 );

    TEST_ASSERT( memcmp( io_seed, check_seed, MBEDTLS_ENTROPY_BLOCK_SIZE ) == 0 );
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_MD_C:MBEDTLS_ENTROPY_NV_SEED:MBEDTLS_PLATFORM_NV_SEED_ALT */
void entropy_nv_seed( data_t * read_seed )
{
#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
    const mbedtls_md_info_t *md_info =
        mbedtls_md_info_from_type( MBEDTLS_MD_SHA512 );
#elif defined(MBEDTLS_ENTROPY_SHA256_ACCUMULATOR)
    const mbedtls_md_info_t *md_info =
        mbedtls_md_info_from_type( MBEDTLS_MD_SHA256 );
#else
#error "Unsupported entropy accumulator"
#endif
    mbedtls_md_context_t accumulator;
    mbedtls_entropy_context ctx;
    int (*original_mbedtls_nv_seed_read)( unsigned char *buf, size_t buf_len ) =
        mbedtls_nv_seed_read;
    int (*original_mbedtls_nv_seed_write)( unsigned char *buf, size_t buf_len ) =
        mbedtls_nv_seed_write;

    unsigned char header[2];
    unsigned char entropy[MBEDTLS_ENTROPY_BLOCK_SIZE];
    unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];
    unsigned char empty[MBEDTLS_ENTROPY_BLOCK_SIZE];
    unsigned char check_seed[MBEDTLS_ENTROPY_BLOCK_SIZE];
    unsigned char check_entropy[MBEDTLS_ENTROPY_BLOCK_SIZE];

    memset( entropy, 0, MBEDTLS_ENTROPY_BLOCK_SIZE );
    memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE );
    memset( empty, 0, MBEDTLS_ENTROPY_BLOCK_SIZE );
    memset( check_seed, 2, MBEDTLS_ENTROPY_BLOCK_SIZE );
    memset( check_entropy, 3, MBEDTLS_ENTROPY_BLOCK_SIZE );

    // Make sure we read/write NV seed from our buffers
    mbedtls_platform_set_nv_seed( buffer_nv_seed_read, buffer_nv_seed_write );

    mbedtls_md_init( &accumulator );
    mbedtls_entropy_init( &ctx );
    entropy_clear_sources( &ctx );

    TEST_ASSERT( mbedtls_entropy_add_source( &ctx, mbedtls_nv_seed_poll, NULL,
                                             MBEDTLS_ENTROPY_BLOCK_SIZE,
                                             MBEDTLS_ENTROPY_SOURCE_STRONG ) == 0 );

    // Set the initial NV seed to read
    TEST_ASSERT( read_seed->len >= MBEDTLS_ENTROPY_BLOCK_SIZE );
    memcpy( buffer_seed, read_seed->x, MBEDTLS_ENTROPY_BLOCK_SIZE );

    // Do an entropy run
    TEST_ASSERT( mbedtls_entropy_func( &ctx, entropy, sizeof( entropy ) ) == 0 );
    // Determine what should have happened with manual entropy internal logic

    // Init accumulator
    header[1] = MBEDTLS_ENTROPY_BLOCK_SIZE;
    TEST_ASSERT( mbedtls_md_setup( &accumulator, md_info, 0 ) == 0 );

    // First run for updating write_seed
    header[0] = 0;
    TEST_ASSERT( mbedtls_md_starts( &accumulator ) == 0 );
    TEST_ASSERT( mbedtls_md_update( &accumulator, header, 2 ) == 0 );
    TEST_ASSERT( mbedtls_md_update( &accumulator,
                                    read_seed->x, MBEDTLS_ENTROPY_BLOCK_SIZE ) == 0 );
    TEST_ASSERT( mbedtls_md_finish( &accumulator, buf ) == 0 );

    TEST_ASSERT( mbedtls_md_starts( &accumulator ) == 0 );
    TEST_ASSERT( mbedtls_md_update( &accumulator,
                                    buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) == 0 );

    TEST_ASSERT( mbedtls_md( md_info, buf, MBEDTLS_ENTROPY_BLOCK_SIZE,
                             check_seed ) == 0 );

    // Second run for actual entropy (triggers mbedtls_entropy_update_nv_seed)
    header[0] = MBEDTLS_ENTROPY_SOURCE_MANUAL;
    TEST_ASSERT( mbedtls_md_update( &accumulator, header, 2 ) == 0 );
    TEST_ASSERT( mbedtls_md_update( &accumulator,
                                    empty, MBEDTLS_ENTROPY_BLOCK_SIZE ) == 0 );

    header[0] = 0;
    TEST_ASSERT( mbedtls_md_update( &accumulator, header, 2 ) == 0 );
    TEST_ASSERT( mbedtls_md_update( &accumulator,
                                    check_seed, MBEDTLS_ENTROPY_BLOCK_SIZE ) == 0 );
    TEST_ASSERT( mbedtls_md_finish( &accumulator, buf ) == 0 );

    TEST_ASSERT( mbedtls_md( md_info, buf, MBEDTLS_ENTROPY_BLOCK_SIZE,
                             check_entropy ) == 0 );

    // Check result of both NV file and entropy received with the manual calculations
    TEST_ASSERT( memcmp( check_seed, buffer_seed, MBEDTLS_ENTROPY_BLOCK_SIZE ) == 0 );
    TEST_ASSERT( memcmp( check_entropy, entropy, MBEDTLS_ENTROPY_BLOCK_SIZE ) == 0 );

exit:
    mbedtls_md_free( &accumulator );
    mbedtls_entropy_free( &ctx );
    mbedtls_nv_seed_read = original_mbedtls_nv_seed_read;
    mbedtls_nv_seed_write = original_mbedtls_nv_seed_write;
}
/* END_CASE */

/* BEGIN_CASE depends_on:ENTROPY_HAVE_STRONG:MBEDTLS_SELF_TEST */
void entropy_selftest( int result )
{
    TEST_ASSERT( mbedtls_entropy_self_test( 1 ) == result );
}
/* END_CASE */